Overwinding preventer for self-winding timepieces



Feb. 22, p F. PHS-TER. 2,702,461

OVERWINDING PREVENTER FOR SELF-WINDING TIMEPIECES Filed March 28, 1952 UnitedStates Patent C) OVERWINDING PREVENTER FOR SELF-WINDING TIMEPIECES Pierre F. Pfister, Sonceboz, Switzerland, assignor to Societe Industrielle de Sonceboz S. A., Sonceboz, Switzerland, a firm of Switzerland Application March 28, 1952, Serial No. 279,076 Claims priority, application Switzerland April 2, 1951 1 Claim. (Cl. 64-28) My invention has for its object a self-winding timepiece provided with means preventing any excess tensioning of the main spring.

According to a main feature of my invention, the winding up gear includes a movable driving member constituted by two coaxial parts interconnected by a spring so as to be capable of executing a relative angular shifting against the action of said spring, one of said parts carrying a catch cooperating for a predetermined relative position of said parts with a driven movable member while it is released with reference to this latter driven member for another relative position of said parts whenever the tension of the main spring of the time-piece is higher than the tension of the spring connecting said parts forming the driving member.

i have illustrated by way of exemplication, in accompanying drawings, a preferred embodiment of the object of my invention. In said drawings:

Fig. 1 is a general view of the time-piece;

Fig. 2 is a view of a detail thereof incorporating the above disclosed novel means.

Fig. 3 is a cross-section through line III-III of Fig. 2;

Fig. 4 is a plan view of the detail illustrated in Fig. 3 when assuming a different position.

The watch illustrated includes a rocking winding up weight 1 pivotally secured to a point at the center of the clockwork and rigid with a pinion 2; the latter drives an arrangement preventing any excess tensioning of the main spring. This arrangement includes a movable driving member constituted by two parts, to wit: a wheel 3 engaging the pinion 2 and a plate 5 (Fig. 3) coaxial with the wheel 3 and connected therewith through the spring 6 so as to allow a slight angular shifting of said plate with reference to the wheel 3. The spring 6 is constituted by an arcuate spring wire engaging at one end a stud 7 rigid with the wheel 3 and at its other end a stud 8 secured to the plate 5. The lower surface of the wheel 3 is provided peripherally with an annular ange 3a recessed at 9 while a catch 11 pivotally secured to the stud 10 on the plate 5 is provided with a nose 11a and a tail-piece 11b.

The movable driven member is constituted by a plate 12 carried coaxially inside the driving movable member and provided with a peripheral notch 13. When the wheel 3 and the plate 5 assume with reference to each other the relative position illustrated in Fig. 2, the tail-piece 11b of the catch 11 abuts against the inner surface of the flange 3a while the nose 11a of said catch engages the notch 13 in the plate 12. As the catch 11 rotates with the plate 5 which is driven in its turn by the wheel 3 through the agency of the spring 6, the plate 12 is also carried along by reason of this engagement. In its turn the plate 12 transmits its movements to the ratchet wheel 14 of the spring drum through means disclosed hereinafter. When the tensioning of the main spring of the watch increases, the spring 6 is also tensioned and the wheel 3 is angularly shifted with reference to the plate 2,702,461 Patented Feb. 22, 1955 ICC 5 so as to bring the recess 9 in its flange 3a into register with the tail-piece 11b of the catch. This tail-piece snaps then into said recess and the nose 11a releases the notch 13 in the plate 12. The movable driving member including the wheel 3 and the plate 5 continues rotating in the winding up direction, i. e. in the direction of the arrow 15 without driving the plate 12. After a complete revolution, two cases are to be considered; in the iirst case, the driving or main spring has suti'ciently expanded for it to be possible for the winding up operation to be resumed and, in the other case on the contrary, the main spring is still sutliciently tensioned for the arrangement preventing excess tensioning to continue being operative. 1n the lirst case, the tensioning of the spring 6 is more considerable than that of the barrel main spring so that the catch 11 is returned into its operative position over the two cooperating slopes provided respectively at 16 on the tail-piece 11b and at 17 on the recess in the ange 3a so that the self-winding operation is resumed as precedingly described.

The plate 12 drives the ratchet wheel or winding wheel 14 through the agency of a pinion 18, the spindle 18a which carries it carrying also rigidly a sleeve 19 lying in alignment with a barrel 12a cast in one with the plate 12. A coil spring 20 surrounds said sleeve 19 and barrel 12a. When the plate 12 revolves in the direction corresponding to the winding up of the clockwork, the spring 2U closes its convolutions whereby the sleeve 19 and consequently the spindle 18a are carried along while in the case of the rotation of the spindle 18a under the action of the rotation of hand-operated winding up means, the convolutions of the spring 20 open so that the barrel 12a does not move with the sleeve 19. The hand-operated winding up means are thus wholly independent in operation with reference to the self-winding means.

What I claim is:

A clutch, especially for preventing excess tensioning of the main spring of a self-winding clockwork, comprising means providing for the transmittal of a torque of a determined maximum amount, said means including a rst driving member constituted by a toothed wneel and including to one side of the wheel, an annular proJecting iange provided with an opening therethrough, a second driving member constituted by a plate coaxial with said toothed wheel, an auxiliary spring connecting said plate and said wheel to allow a relative shifting thereof against the tension of said auxiliary spring, a driven plate coaxial with the two driving members and provided with a peripheral notch, a catch pivotally secured to the plate and including a tail-piece engaging slidingly the iiange on the toothed wheel and adapted for a tirst predetermined angular position between said two driving members to engage positively the opening in the ange, said catch being adapted to engage the notch in the driven plate for another predetermined relative position between the two driving members, the torque to be transmitted and the auxiliary spring acting in opposite directions on the second driving member to shift it into either of said angular positions with reference to the first member according to the amount of said torque.

References Cited in the le of this patent UNITED STATES PATENTS 2,582,077 Smith Ian. 8, 1952 FOREIGN PATENTS 218,553 Great Britain July 10, 1924 461,474 Canada 1949 

